There's a section of Hawaiian Mysticism that talks about the three selves: The Younger Self, The Waking Self, and The Higher Self. If you want to maintain a sense of wonder and generosity, than you should make some time for your inner child. This is also prescribed if you are having trouble forgiving someone, since only your inner child is capable of forgiveness.
My only suggestion is to look at others that are clearly less fortunate than you are.
Like the guy who keeps on complaining about how sore his legs are feeling.
To the guy who has no legs!
Count your many blessings name them one by one,
count your many blessings see what GOD has done!
In everything that GOD gives you in this life do your best to give thanks!
They say that when you are having a hard time you should continue to praise the Lord.